A fungicidal composition formulation containing prothioconazole and sulfur and a method of preparing the same

Abstract

This invention relates to the technical field of fungicides, and more particularly to a fungicide composition formulation containing prothioconazole and sulfur, and its preparation method. The composition formulation includes an active ingredient, a modified Kraft lignin carrier, a surfactant, a fixative, and water. The active ingredient is loaded onto the modified Kraft lignin carrier to form nanoparticles, the average particle size of which is 50-500 nm. The modified Kraft lignin carrier is acetylated Kraft lignin, with a mass ratio of (0.25-15):1 to the active ingredient. The active ingredient is prothioconazole and sulfur, with a mass ratio of (0.03-15):1. The formulation obtained through this preparation process effectively overcomes the defects of traditional fungicides, such as unstable efficacy and poor scour resistance. While improving dispersibility, stability, and sustained-release performance, it significantly enhances the field utilization efficiency of the active ingredient.

Description

Technical Field

[0001] This invention relates to the technical field of fungicides, and more particularly to a fungicidal composition formulation containing prothioconazole and sulfur, and a method for preparing the same. Background Technology

[0002] Agricultural fungicides play a crucial role in ensuring food security and crop yields. However, traditional fungicides suffer from low utilization rates of their active ingredients, and long-term, excessive use can lead to increased environmental residues and the risk of non-target organisms, causing environmental and ecological problems. Therefore, developing novel formulations that are highly efficient, low in toxicity, and can significantly reduce the amount of active ingredients required has become a core direction for the development of green agriculture.

[0003] Triazole fungicides are a class of systemic fungicides widely used in agricultural production to control various fungal diseases on vegetables, fruits, grains, soybeans, corn, and other crops. Prothioconazole, as a representative of triazole fungicides, is widely used to control rust, powdery mildew, and leaf spot, among other fungal diseases, due to its excellent systemic properties and broad-spectrum activity. However, prothioconazole has a certain degree of environmental persistence; long-term, high-dose application not only increases environmental burden but also poses health risks. Improving utilization while ensuring efficacy is a pressing issue that needs to be addressed.

[0004] Currently, conventional fungicide formulations are mostly in the form of emulsifiable concentrates, suspension concentrates, wettable powders, and water-dispersible granules. Although these formulations are widely used in agricultural production, they still have significant drawbacks: first, some active ingredients have poor water solubility and insufficient dispersion stability; second, their adhesion to leaves and resistance to rain washout are weak; and third, their release rate is too fast, resulting in a short duration of effectiveness. These shortcomings often force farmers to increase application rates to maintain efficacy, thereby increasing costs and ecological pressure.

[0005] Therefore, improving the stability of fungicides through formulation technology, thereby enhancing the field application efficiency of their active ingredients, is a technological bottleneck that the industry urgently needs to overcome. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a bactericidal composition containing prothioconazole and sulfur, thereby overcoming the shortcomings of the prior art.

[0007] To achieve the above objectives, the present invention provides a bactericidal composition formulation containing prothioconazole and sulfur, comprising an active ingredient, a modified Kraft lignin carrier, a surfactant, a fixative, and water; the active ingredient is loaded onto the modified Kraft lignin carrier to form nanoparticles, the average particle size of the nanoparticles being 50 nm to 500 nm; the modified Kraft lignin carrier is acetylated modified Kraft lignin, and the mass ratio of the active ingredient to the active ingredient is (0.25-15):1; the active ingredient is prothioconazole and sulfur, and the mass ratio of the two is (0.03-15):1.

[0008] Furthermore, the mass ratio of the modified Kraft lignin carrier to the active ingredient is 12:1 to 1:1.

[0009] Furthermore, the mass ratio of the modified Kraft lignin carrier to the active ingredient is 8.3:1.

[0010] Furthermore, the surfactant includes one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, Tween emulsifiers, and polyoxyethylene ether surfactants.

[0011] Furthermore, the fixative includes one or more of polyvinylpyrrolidone, polyvinyl alcohol, xanthan gum, sodium carboxymethyl cellulose, and sodium alginate.

[0012] Furthermore, the concentration of the surfactant in the bactericidal composition is 0.01~1.0 wt%; the amount of the fixative is 0.1%~5% of the total mass of the bactericidal composition.

[0013] This invention also provides a method for preparing the bactericidal composition containing prothioconazole and sulfur, comprising the following steps: S1, mixing Kraft lignin with acetone, stirring and dispersing, then filtering to remove soluble impurities and obtain a filter cake; washing and drying the filter cake to obtain purified Kraft lignin; S2, dispersing the purified Kraft lignin in an organic solvent, adding an acetylation reagent and a catalyst, and carrying out an acetylation reaction under stirring conditions to acetylate and replace the hydroxyl groups in the Kraft lignin molecules; after the reaction, precipitation, filtration, and washing are performed. S3. The modified Kraft lignin carrier is washed and dried to obtain an acetylated Kraft lignin carrier; S4. The modified Kraft lignin carrier and the active ingredient are mixed according to the mass ratio, and a surfactant, fixative and water are added to form a mixed system containing the modified Kraft lignin carrier and the active ingredient; wherein the active ingredient includes prothioconazole and sulfur; S5. The mixed system obtained in step S3 is dispersed to load the active ingredient in the modified Kraft lignin carrier and form a nanoscale dispersion system with the modified Kraft lignin carrier to obtain the bactericidal composition formulation.

[0014] Further, in step S2, the purified Kraft lignin is dispersed in 1,4-dioxane, acetic anhydride and N-methylimidazole are added, and an acetylation reaction is carried out under stirring conditions; after the reaction is completed, it is acidified with hydrochloric acid, and then precipitated, filtered, washed and dried to obtain the acetylated modified Kraft lignin carrier.

[0015] Furthermore, in step S4, the dispersion process includes one or more of high-speed shearing, ultrasonic dispersion, and high-pressure homogenization dispersion.

[0016] Furthermore, the average particle size of the nanoparticles in the prepared bactericidal composition formulation is 50 nm to 500 nm.

[0017] The present invention has the following advantages: 1. This invention achieves a synergistic effect by combining prothioconazole with sulfur, and effectively controls the release rate of active ingredients and reduces the risk of rainwater runoff and photodegradation loss by combining the nano-encapsulation structure of modified Kraft lignin carrier, thereby significantly extending the duration of efficacy. This formulation effectively overcomes the defects of traditional fungicides such as unstable efficacy and poor erosion resistance. While comprehensively improving dispersibility, stability and sustained-release performance, it greatly enhances the field utilization efficiency of active ingredients. It not only ensures the long-lasting stability of efficacy and reduces the frequency of application, but also maintains excellent control efficacy while reducing the total amount of pesticide used, effectively reducing the environmental burden.

[0018] 2. The antibacterial composition of this invention eliminates the toxic organic solvents (such as benzenes and ketones) and synthetic surfactants widely used in traditional emulsifiable concentrates or suspensions. Instead, it selects Kraft lignin, derived from papermaking byproducts, as the core carrier. This not only achieves high-value utilization of waste biomass but also significantly reduces the safety risks to crops and non-target organisms by leveraging its natural biocompatibility and low toxicity. This allows the formulation to greatly reduce agricultural non-point source pollution while ensuring food security, demonstrating significant ecological benefits.

[0019] 3. The preparation method of the present invention has a short process flow, is easy to scale up for industrial production, and has mild reaction conditions, which effectively reduces production costs and energy consumption.

[0020] 4. The preparation method of the present invention ensures the uniformity of nanoparticle size during the preparation process and prevents agglomeration by introducing the synergistic regulation of fixatives and surfactants. Attached Figure Description

[0021] Figure 1 The process flow diagram for preparing the prothioconazole / sulfur-acetylated Kraft lignin antibacterial composition provided by the present invention is shown below. Figure 2This is a statistical chart showing the yield of Examples 1-5 in the field experiment. Detailed Implementation

[0022] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0023] For experiments where specific experimental steps or conditions are not specified in the examples, the procedures or conditions described in the literature in this field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagents. Experimental methods without specified conditions generally follow methods known in this field.

[0024] In this invention, the Kraft lignin can be industrial Kraft lignin, preferably Kraft lignin derived from the wood pulping process. The active ingredients are prothioconazole and sulfur. The bactericidal composition of the product is preferably a water-based emulsion-type nano-formulation. The preparation process is as follows: Figure 1 As shown. Unless otherwise stated, all percentage contents mentioned in the following examples are by mass percentages.

[0025] Example 1

[0026] S1. Purification of Kraft lignin: Weigh industrial Kraft lignin (purchased from Shandong Longli Biological Reagent Co., Ltd.), add it to acetone, stir and disperse evenly to ensure sufficient contact between Kraft lignin and acetone, thereby removing low molecular weight impurities, soluble organic impurities, and some pigment components; after stirring, filter and collect the solid filter cake; wash the obtained filter cake repeatedly with acetone 1-3 times, and then wash with deionized water until the filtrate shows almost no obvious color change. Subsequently, place the washed solid under vacuum drying at 60℃ for 6 h to obtain purified Kraft lignin.

[0027] S2. Preparation of acetylated Kraft lignin carrier: Purified Kraft lignin was weighed and added to 1,4-dioxane, stirred until fully dissolved to form a Kraft lignin dispersion. Acetic anhydride and N-methylimidazole were added to the dispersion, wherein the molar ratio of acetic anhydride to reactive hydroxyl groups in Kraft lignin was 1.5~4.0:1, and the molar ratio of N-methylimidazole to acetic anhydride was 0.1~0.2:1. The acetylation reaction was carried out under stirring. After the reaction was completed, dilute hydrochloric acid was added to the reaction system for acidification to precipitate the product. The solid product was then collected by filtration. The obtained solid was washed successively with water and ethanol to remove residues. The washed solid was vacuum dried at 60℃ for 6 h to obtain the acetylated modified Kraft lignin carrier.

[0028] Preparation of S3, Prothioconazole / Sulfur-Acetylated Kraft Lignin Antibacterial Composition: Weigh 4.67 g of acetylated Kraft lignin carrier KAL and 0.33 g of active ingredient (of which the mass ratio of prothioconazole to sulfur is 1:30, i.e., 0.011 g of prothioconazole and 0.319 g of sulfur) technical grade. Mix KAL with prothioconazole and sulfur, and add deionized water, sodium dodecyl sulfate, and polyvinylpyrrolidone to the mixture. Sodium dodecyl sulfate is used as a surfactant, and polyvinylpyrrolidone is used as a fixative. The amount of sodium dodecyl sulfate is 1.0 wt%, and the amount of polyvinylpyrrolidone is 5 wt%.

[0029] S4. The obtained system is subjected to high-speed shear dispersion and further dispersion treatment to achieve uniform dispersion of prothioconazole, sulfur, and KAL in the aqueous phase, forming a continuous aqueous nano-dispersion system in which the active components are stably distributed in the aqueous phase as nano-sized particles. During the dispersion process, under the synergistic effect of sodium dodecyl sulfate and polyvinylpyrrolidone, the system forms a stable interfacial structure, controlling the particle size within the range of 50–500 nm. After dispersion, a prothioconazole / acetone-acetylated Kraft lignin composition formulation is obtained. This composition formulation can be stored directly as a mother liquor or diluted with water for foliar spraying as needed for field application.

[0030] It should be noted that, in this embodiment, the surfactant can be any one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, Tween emulsifiers, and polyoxyethylene ether surfactants; the fixative can be any one or more of polyvinylpyrrolidone, polyvinyl alcohol, xanthan gum, sodium carboxymethyl cellulose, and sodium alginate. In step S4, the dispersion treatment includes any one or more of high-speed shearing, ultrasonic dispersion, and high-pressure homogenization dispersion.

[0031] Example 2

[0032] Example 2 uses the same preparation process as Example 1, except for step S3, as detailed below: Preparation of S3, Prothioconazole / Sulfur-Acetylated Kraft Lignin Antibacterial Composition: Weigh 4.62 g of acetylated Kraft lignin carrier KAL and 0.38 g of active ingredient (where the mass ratio of prothioconazole to sulfur is 1:9, i.e., 0.038 g of prothioconazole and 0.342 g of sulfur) technical grade. Mix KAL with prothioconazole and sulfur, and add deionized water, sodium dodecyl sulfate, and polyvinylpyrrolidone to the mixture. Sodium dodecyl sulfate is used as a surfactant, and polyvinylpyrrolidone is used as a fixative. The amount of sodium dodecyl sulfate is 0.5 wt%, and the amount of polyvinylpyrrolidone is 2 wt%.

[0033] Example 3

[0034] Example 3 is prepared using the same process as Example 1, except for step S3, as detailed below: Preparation of S3, Prothioconazole / Sulfur-Acetylated Kraft Lignin Antibacterial Composition: Weigh 4.46 g of acetylated Kraft lignin carrier KAL and 0.54 g of active ingredient (of which the mass ratio of prothioconazole to sulfur is 4:1, i.e., 0.432 g of prothioconazole and 0.108 g of sulfur) technical grade. Mix KAL with prothioconazole and sulfur, and add deionized water, sodium dodecyl sulfate, and polyvinylpyrrolidone to the mixture. Sodium dodecyl sulfate is used as a surfactant, and polyvinylpyrrolidone is used as a fixative. The amount of sodium dodecyl sulfate is 0.5 wt%, and the amount of polyvinylpyrrolidone is 2 wt%.

[0035] Example 4

[0036] Example 4 uses the same preparation process as Example 1, except for step S3, as detailed below: Preparation of S3, Prothioconazole / Sulfur-Acetylated Kraft Lignin Antibacterial Composition: Weigh 1 g of acetylated Kraft lignin carrier KAL and 4 g of active ingredient (of which the mass ratio of prothioconazole to sulfur is 12:1, i.e., 3.7 g of prothioconazole and 0.30 g of sulfur) technical grade. Mix KAL with prothioconazole and sulfur, and add deionized water, sodium dodecyl sulfate, and polyvinylpyrrolidone to the mixture. Sodium dodecyl sulfate is used as a surfactant, and polyvinylpyrrolidone is used as a fixative. The amount of sodium dodecyl sulfate is 0.01 wt%, and the amount of polyvinylpyrrolidone is 0.1 wt%.

[0037] Example 5

[0038] Example 5 uses the same preparation process as Example 1, except for step S3, as detailed below: Preparation of S3, Prothioconazole / Sulfur-Acetylated Kraft Lignin Antibacterial Composition: Weigh 1 g of acetylated Kraft lignin carrier KAL and 4 g of active ingredient (where the mass ratio of prothioconazole to sulfur is approximately 15:1, i.e., 3.75 g of prothioconazole and 0.25 g of sulfur) technical grade. Mix KAL with prothioconazole and acetone, and add deionized water, sodium dodecyl sulfate, and polyvinylpyrrolidone to the mixture. Sodium dodecyl sulfate is used as a surfactant, and polyvinylpyrrolidone is used as a fixative. The amount of sodium dodecyl sulfate is 0.01 wt%, and the amount of polyvinylpyrrolidone is 0.1 wt%.

[0039] Comparative Example 1 The difference between Comparative Example 1 and Example 3 is that S2 was not set, that is, only purified unacetylated Kraft lignin was used as a carrier to prepare the prothioconazole / sulfur-Kraft lignin antibacterial composition.

[0040] Comparative Example 2 The difference between Comparative Example 2 and Example 3 is that S4 was not set, that is, the system obtained in S3 was not subjected to high-speed shear dispersion and emulsification dispersion treatment.

[0041] Performance testing 1. Determination of particle size, zeta potential, and encapsulation efficiency of antibacterial composition formulations The particle size, zeta potential, and encapsulation efficiency of the antibacterial composition formulations prepared in Examples 1-5 were determined. Particle size was determined by dynamic light scattering. Zeta potential was determined by electrophoretic light scattering. Encapsulation efficiency was determined by high-performance liquid chromatography. The encapsulation efficiency of the active ingredient in the modified Kraft lignin carrier was calculated by measuring the content of active ingredient in the total formulation system and the content of free active ingredient. The test results are shown in Table 1.

[0042] Encapsulation efficiency can be calculated using the following formula: Encapsulation efficiency (%) = (mass of added active ingredient - mass of free active ingredient) / mass of added active ingredient × 100%.

[0043] Table 1. Statistical table of antibacterial composition performance tests in Examples 1-5 and Comparative Examples 1-2

[0044] As shown in Table 1, the antibacterial compositions prepared in Examples 1-5 all exhibited excellent nanoscale dispersion characteristics. Specifically, the particle sizes of Examples 2 and 3 were concentrated at 158.07 nm and 168.48 nm, respectively, and the polydispersity index (PDI) was low, indicating that the system had high homogeneity. Meanwhile, the absolute values ​​of the Zeta potentials in all examples were between 30 mV and 40 mV, which is attributed to the negative charge repulsion on the surface of the modified Kraft lignin carrier, effectively preventing the aggregation of nanoparticles and thus endowing the formulation with colloidal stability for long-term storage. In contrast, the particle size of Comparative Example 1 (unmodified) and Comparative Example 2 (insufficiently dispersed) increased significantly to over 484 nm, even reaching the micrometer level (1214 nm), indicating that the dispersion system had severe agglomeration or insufficient dispersion. Although the absolute value of their Zeta potential was high, the particle size results suggested that the system was in a non-uniform aggregated state, leading to the potential measurement results deviating from the true dispersed particle state. This result indicates that acetylated modified Kraft lignin carrier and optimized dispersion process play a key role in constructing a stable nano-dispersion system.

[0045] Regarding encapsulation performance, Examples 2 (98.2%) and 3 (100%) exhibited extremely high loading rates of active ingredients. This data confirms the interaction between the acetylated Kraft lignin carrier and prothioconazole and sulfur, achieving effective loading of the active ingredients. Based on this dense nanostructure, the formulation of this invention can avoid burst release of active ingredients after application, prolong the effective retention time of the agent on the crop surface, and indirectly improve the utilization efficiency of active ingredients by reducing non-target loss.

[0046] Comparing the data from Example 3 with Comparative Example 1 (unmodified lignin) and Comparative Example 2 (undispersed), it was found that the particle size of Comparative Examples 1 and 2 was significantly increased (>480 nm), and the encapsulation efficiency was extremely low (<50%). This deterioration in physical properties directly led to a significant decrease in its biological activity (control efficacy less than 35%). This conversely proves that the acetylation modification process and nano-dispersion technology used in this invention endow the formulation with excellent anti-settling and erosion resistance potential. Only when the active ingredient is firmly locked in the modified lignin nanoparticles can the agent form a strong film on the leaf surface, resisting rainwater erosion, thereby ensuring the long-lasting and stable control efficacy in the field.

[0047] 2. Trial on the control effect of maize leaf spot disease Using maize leaf spot as the target disease, the antibacterial composition formulations obtained in Examples 1-5 and Comparative Examples 1-3 were tested to verify their control efficacy.

[0048] In the greenhouse experiment, maize was planted in seedling containers. After the plants grew to the point where the leaves were fully expanded, they were sprayed with Examples 1-5, Comparative Examples 1-3, and a blank control, respectively. The spraying concentration for Examples 1-5 and Comparative Examples 1-2 was 120 g / hm². 2 (Based on the mass of the formulation). 48 h after application, inoculate with a suspension of spores of the corn leaf blight pathogen. Maintain a high humidity environment after inoculation to promote disease development. 10 days after inoculation, investigate the number of leaf spots and the severity of the disease, and calculate the control effect.

[0049] Table 2 Greenhouse tests of antibacterial compositions in Examples 1-5 and Comparative Examples 1-2

[0050] The results of the greenhouse experiment are shown in Table 2. Compared with the blank control, Examples 1-5 all significantly reduced the number of lesions on maize leaves and decreased the severity of the disease. Among them, Example 3 showed the best lesion control and disease severity reduction effect under greenhouse conditions.

[0051] Analysis of the test results in Tables 1 and 2 shows that the antibacterial composition formulation prepared in the embodiments of the present invention (especially Example 3) has an average particle size controlled within the range of 150-200 nm and a high absolute value of Zeta potential (approximately -38 mV). This nanoscale particle size distribution and excellent colloidal stability greatly increase the coverage density and contact area of ​​the active ingredients (prothioconazole and sulfur) on plant leaves. Compared with traditional large-particle formulations, the nanoparticles of the present invention can spread more evenly on the leaf surface, overcoming the deficiency of insufficient dispersion stability in traditional technologies. This improvement in physical morphology is the basis for Example 3 exhibiting the highest lesion reduction rate (76.2%) and severity reduction percentage (77.7%) in greenhouse trials.

[0052] Meanwhile, in this embodiment of the invention, the co-loading of prothioconazole and sulfur on a lignin-based nanocarrier produces a significant synergistic effect. The sulfur component can disrupt the cell structure of pathogens, assisting prothioconazole in more easily penetrating the pathogen cell wall, thereby enhancing the systemic therapeutic effect of prothioconazole. This synergistic effect, combined with the high permeability of the nanocarrier, enables the formulation of this invention to exhibit excellent eradication and protective efficacy against stubborn fungal diseases such as corn leaf blight.

[0053] In field trials, Examples 1-5 were compared with a blank control. The trials employed a randomized block design, and maize yield was measured at harvest after pesticide application. The results are as follows: Figure 2 As shown.

[0054] Field trial results showed that Examples 1-5 all reduced the severity of maize diseases. Example 3 showed the most significant improvement under field conditions. Yield results indicated that the treatment in Example 3 significantly increased maize yield, reaching approximately 6438 kg / ha, and exhibited a higher yield level compared to the control group and Comparative Example 3. This demonstrates that the prothioconazole / sulfur-acetylated Kraft lignin antibacterial composition of the present invention not only has good disease control effects but also has the potential to increase crop yield.

[0055] In summary, the fungicidal composition containing prothioconazole and sulfur prepared in the embodiments of the present invention (especially Example 3) successfully integrates high dispersibility, high stability (high zeta potential), high utilization rate (high loading efficiency), and excellent control efficacy (low lesion number, high yield) into a complete technical loop through the technical solution of modifying Kraft lignin nanocarriers. This formulation not only solves the problem of poor efficacy and stability of traditional fungicides, but also achieves environmentally friendly application by eliminating toxic organic solvents, fully meeting the development needs of green agriculture.

[0056] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A bactericidal composition containing prothioconazole and sulfur, characterized in that, It includes an active ingredient, a modified Kraft lignin carrier, a surfactant, a fixative, and water; the active ingredient is loaded onto the modified Kraft lignin carrier to form nanoparticles, the average particle size of which is 50 nm to 500 nm. The modified Kraft lignin carrier is acetylated Kraft lignin, and the mass ratio of the carrier to the active ingredient is (0.25-15):

1. The active ingredients are prothioconazole and sulfur, with a mass ratio of (0.03-15):

1.

2. The bactericidal composition formulation containing prothioconazole and sulfur according to claim 1, characterized in that, The mass ratio of the modified Kraft lignin carrier to the active ingredient is 12:1 to 1:

1.

3. The bactericidal composition formulation containing prothioconazole and sulfur according to claim 2, characterized in that, The mass ratio of modified Kraft lignin carrier to active ingredient is 8.3:

1.

4. The bactericidal composition formulation containing prothioconazole and sulfur according to claim 1, characterized in that, The surfactant includes one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, Tween emulsifiers, and polyoxyethylene ether surfactants.

5. The bactericidal composition formulation containing prothioconazole and sulfur according to claim 1, characterized in that, The fixative includes one or more of polyvinylpyrrolidone, polyvinyl alcohol, xanthan gum, sodium carboxymethyl cellulose, and sodium alginate.

6. The bactericidal composition formulation containing prothioconazole and sulfur according to claim 1, characterized in that, The concentration of the surfactant in the bactericidal composition is 0.01~1.0 wt%; the amount of the fixative is 0.1~5% of the total mass of the bactericidal composition.

7. The method for preparing the bactericidal composition formulation containing prothioconazole and sulfur according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Mix Kraft lignin with acetone, stir to disperse, and then filter to remove soluble impurities to obtain a filter cake; wash and dry the filter cake to obtain purified Kraft lignin. S2. The purified Kraft lignin is dispersed in an organic solvent, an acetylation reagent and a catalyst are added, and an acetylation reaction is carried out under stirring conditions to acetylate and replace the hydroxyl groups in the Kraft lignin molecules. After the reaction is completed, the acetylated Kraft lignin carrier is obtained by precipitation, filtration, washing and drying. S3. The modified Kraft lignin carrier and the active ingredient are mixed in a certain mass ratio, and surfactant, fixative and water are added to form a mixed system containing the modified Kraft lignin carrier and the active ingredient; wherein, the active ingredient includes prothioconazole and sulfur; S4. The mixed system obtained in step S3 is dispersed to load the active ingredient onto the modified Kraft lignin carrier, forming a nanoscale dispersion system with the modified Kraft lignin carrier, thereby obtaining the bactericidal composition formulation.

8. The preparation method according to claim 7, characterized in that, In step S2, the purified Kraft lignin is dispersed in 1,4-dioxane, acetic anhydride and N-methylimidazole are added, and an acetylation reaction is carried out under stirring conditions. After the reaction is completed, the lignin is acidified with hydrochloric acid, and then precipitated, filtered, washed and dried to obtain the acetylated modified Kraft lignin carrier.

9. The preparation method according to claim 7, characterized in that, In step S4, the dispersion process includes one or more of high-speed shearing, ultrasonic dispersion, and high-pressure homogenization dispersion.

10. The preparation method according to claim 9, characterized in that, The average particle size of the nanoparticles in the prepared bactericidal composition formulation is 50 nm to 500 nm.

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